Method of and means for working curved surfaces



Jan.- 19,1926. 1,570,242

P. GOERZ ET AL METHOD OF AND MEANS FOR WORKING CURVED SURFACES Filed Oct. 4, 192,3 1 2 Sheets-Sheet 1 Fig. 1

5 3 Inventors:

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Jan. 19 I926; 1,570,242

v P. GOERZ ET AL METHOD OF AND umns FOR wommxe CURVED summons Filed 001;. 9 2 Sheets-Sheet z Int/anions:

K k r Patented Jan. 19, 1926.

UNITED STATES 1,570,242 PATENT OFFICE.

PAUL GOERZ, OF GRUNEWALD, NEAR BERLIN, AND ERNST JACOBI, FRIEDENAU, NEAR BERLIN, GERMANY, ASSIGNORS TO THE FIRM OF OPTISGHE ANSTALT C. P; GOERZ AKTIENGESELLSCHAFT, OF FRIEDENAU, NEAR BERLIN, GERMANY.

METHOD OF AND MEANS FOR W'ORKING CURVED SURFACES.

Application filed. October 4., 1923. Serial 1%. 666,439.

T all whom it may concern:

Be it known that we, PAUL Gonnz, a citizen of the German Republic, and resident of Grunewald, near Berlin, Germany, and

Dr. ERNST JACOBI, a citizen of the German Republic, and resident of Friedenau, near Berlin, Germany, have I invented certain new and useful Improvements in and Relating to Methods of and Means for 3.0 Vorking Curved Surfaces (for which application for patenthas been filed in Germany, August 11th, 1922), of which the fol lowing is a specification.

This invention relates to the working of articles of all kinds, (more particularly glass articles) to be planed, ground or polished, and aims at simplifying and expediting the grinding procedure and also replacing manual labour by machinery for working lenses. i

According to the invention the grinding, polishing etc. is effected; by pressing the work by centrifugal force against a continously rotating grinding, or polishing surface and simultaneously movingit rela tively to the grinding means or tool having the rotary grinding surface. In order that the invention may be fully understood we have illustrated on the annexed drawing several constructional examples of grinding or polishing apparatus working on the new principle. 7

Fig. 1 is a sectional elevation through one form ofgrinding apparatus according to the invention.

Fig. 2 is a plan of the same with parts broken off.

Fig. 3 is a modification of the construction shown in Figs. 1 and 2.

Figs. 4: and 5 are a partially sectional elevation and a partial plan respectively of a further construction of the grinding apparatus according to the invention, particularly suitable for grindng concave lenses.

Figs. 6, 7 and 8 illustrate modified forms of grinding cups or tools.

Referring to. the construction of Figs. 1 and 2, the main shaft 1 of the grinding apparatus is fitted with a support or carrier 2 on the lower face of which is rotatably mounted a gear wheel 3 meshing with a gear wheel a rigidly mounted 011 the frame of the apparatus and meshing with a gear wheel 5 rotatably mounted on the support 2. The last-mentioned gear wheel is on; a pin 6 on which a grinding cup or tool is mounted. The work 8 is assumed to be a spectacle lens. The top of the said cup is fitted with an inwardly projecting flange 9. c

The apparatus works as follows: The shaft 1 is rotated, together with the support 2 and with the grinding cup 7 rotatably mounted thereon. Owing to the gear 8, 4, 5, the said grinding cup rotates simultaneously around the said shaft 1 and about its axis (pin 6), thus performing what-is 'eneraly termed a planet-wheel motion, The work or lens 8 to be ground is loosely placed in the cup or tool 7 and since it pal-takes in the rotation of the support 2, it is centrifugally pressed against the inner wall of the said cup. Since the latter isrotated also about its own axis, there is a tendency for the lens! 8 to move relatively to the wall of the said cup 7. In the construction illustrated the angular mo'tion of the cup? about the pin 6 is opposite to that of the support 2 rotating about the shaft 1. In this construction it isquite' easy to regulate the speed so that the lens 8 remains station ary relatively to the tool while the inner face of the latter moves relatively to the said lens or work. Then the latter has a substantially circular edge, the flange 9 of the tool or cup as illustrated causes the work to roll on the said flange so that there is a double relative motion of the work to the cup. This applies of course to the grinding, of a spherical surface, the work done being particularly accurate and intensive.

The same apparatus, with a differently shaped cup, may be used for grinding toric surfaces. As regards the flange .9, it is necessary for. the lens to be ground tobear on the said flange with a rectilinear edge to prevent the edge from rolling on the surface ofthe flange.

Surfaces of dissimilar curvatnre may be ground simultaneously by replacing the one-surface grinding cup of Fig.- 1 by a cup as shown in Fig. 7 in whicha plurality of grinding surfaces surround one another.

A modification o the construction shown in Figs. 1 and 2 is illustrated in Fig. 3 in which the work. is supported in a holder pivotally mounted on the main support 2 of the grinding apparatus. The support 2, the cup or tool 7 and its pin 6, and the gear wheels 3 and 5 for rotating the cup about its axis are the same as in Figs. 1 and 2, the two types of holders 12 and 13 being an addition thereto. The first-mentioned holder 12 is constituted by a twoarmed lever pivoted on the main support 2 at 14, the work 16 being carried by suitable gripping means 15 at one end of the lever while the other end thereof is fitted with a weight 17, which is oscillated outwards when the support 2 is rotated. The Weight of the gripping means 15 and work 16 being overcome by the weight 17, the said work or lens is pressed against the outer face of the cup 7 by the heavier component. The outer face of the grinding cup rotating relatively to the lens 16, the latter is worked as in the construction of Figs. 1 and 2.

The work holder 13 disposed between the centre of the support 2 and the cup 7 is a one-armed lever and is likewise provided with gripping means 18 holding the work 19. This holder is also subjected to the action of centrifugal force which tends to throw it outwards, with the result that the work 19 is directly pressed against the outer face of the grinding cup or tool 7. There is no need for this lever to be double-armed and weighted.

Referring to the construction shown in Figs. 4: and 5, the various elements of the grinding apparatus are differently shaped and mounted than as shown in Figs. 1, 2 and 3, the toothed wheel gear being moreover replaced by frictional driving means. The driving shaft 1 of the apparatus is fitted with a support 2 and with a pin 6 carrying the grinding means and a friction wheel 5 in frictional contact with the flange 20 surrounding the support 2 and belonging to a carrier 21 rotated by any desired means about the driving shaft 1. The work 8 bears against the grinding means 7 and is located in a recess 23 provided on a suitable part of the main support 2. The working is in principle the same as that of the apparatus shown in Figs. 1, 2 and 8. The work 8' partakes in the rotation of the main support 2 and is pressed by centrifugal force against the outer face of the grinding means 7 which moves angularly relatively to the Work 8 which is in the recess 23 and therefore prevented from moving laterally. The angular speed of the grinding means 7 and therefore the speed at which the machine works may be altered within very wide limits without changing the friction wheel 5, owing to the carrier 21 being rotatably mounted.

The grinding cup of 6 is in the shape of a vertical cylinder and renders it possible to grind not only cylindrical lenses but also spherical lenses, by starting from a blank whicn has a greater curvature than the cylindrical surface on which the said blank is ground. The lens or blank 8 is rotated inside the grinding cylinder and it is ground to the curvature of the said cylinder. A hollow cylinder of this kind has proved par: ticularly suitable, in connection with the production of spherical surfaces, for polishing the said surfaces after they are finely ground. A number of grinding units or tools may be arranged in a circle around the shaft 1 for the purpose of increasing the efficiency of the grinding apparatus hereinbefore described. The grinding cup of Fig. 8 has a smooth horizontal i'ioor, whereby it is not only possible to work the curved edge of the work in'the cup by the vertical wall 11 of the said cup, but also to grind the face of the work in contact withthe smooth floor 10 of the said grinding cup.

What we claim is 1. A method of working lenses and like spherically curved articles by means of a grinding cup having av peripheral wall consisting in loosely putting a blank to be worked upon into the grinding cup and subjecting said cup with the blank loosely put therein to rotational motion of such velocity that the blank is centrifugally pressed against the peripheral wall of the cup, the wall having at the same time an advancing motion communicated to it with relation to the point of intersection of the cup wall and the direction of the centrifugal force pressing the blank against said wall.

2. A method of working lenses and like spherically curved articles by means of a grinding cup, having a spherically curved peripheral wall, consisting in loosely putting a blank to be worked upon into the grinding cup and subjecting said cup with the blank loosely put therein to rotational motion of such velocity that the blank is centrifugally pressed against the peripheral wall of the cup, the wall having at the same time an advancing motion communicated to it with relation to the point of intersection of the cup and the direction of the centrifugal force pressing the blank against said wall.

3. A method of working lenses and like spherically curved articles by means of a grinding cup, having aperipheral wall, consisting in loosely putting a blank to be worked upon into the grinding cup and subjecting said cup to a planetary motion including a motion around its own axis of such velocity that the blank within said cup is centrifugally pressed against the peripheral wall of the cup under the action of the rotation of the cup about the main axis of the system outside the axis of the cup.

4;. A grinding or polishing device comprising a cup shaped grinding tool adapted to receive in its cavity a work piece or blank to be worked upon, said cup having a peripheral working surface of circular cross section, a carrier for said grinding cup mounted for rotational movement so as to guide the grinding cup along a recurrent path, the cup being so mounted on said carrier and otherwise so engaged that the axis of the Working surface of the cup remains at all times at right angles to the rotational plane of the carrier and that the working surface of the cup at the point of intersection with the direction of centrifugal force produced by the rotational movement experiences displacement laterally to said direction of centrifugal force.

5. A grinding or polishing device comprising a cup shaped grinding tool adapted to receive in its cavity a work piece or blank to be worked upon, said cup having a spherically curved peripheral working surface, a carrier for said grinding cup mounted for rotational movement so as to guide the grinding cup along a recurrent path, the cup being so mounted on said carrier and otherwise so engaged that the axis of the working surface of the cup re mains at all times; at right angles to the rotational plane of the carrier and that the working surface of the cup at the point of intersection with the direction of centrifugal force produced by the rotational movement experiences displacement laterally to said direction of centrifugal force.

6. A grinding or polishing device comprising a cup shaped grinding tool adapted to receive in its cavity a work piece or blank to be worked upon, said cup having a spherically curved peripheral working surface, a. carrier for said grinding cup mounted for rotational movement so as to guide the grinding cup along a recurrent path, the cup being so mounted on said carrier and otherwise so engaged that the axis of the working surface of the cup remains at all times at right angles to the rotational plane of the carrier and that the working surface of the cup at the point of intersection with the direction of centrifugal force produced by the rotational movement experiences displacement laterally to said direction of centrifugal force, the upper edge of the cup being provided with an in- V wardly, turned flange adapted to form a. stop member for the blank within the cup riding upwardly along the wall under centrifugal action.

In testimony where-of we have signed tlus specification.

PAUL GOERZ. DR. ERNST JACOBI. 

